If you thought that science-fiction began with Victor Hugo and H. G. Wells, you need to read this insightful survey of ten books ranging from the 1630s to 1909. Most of these titles rank as 'hard science fiction' considering the state of knowledge when written, and the list of authors might shock you.
I am definitely up for more reviews by Edward Wozniak. There is so much science-fiction out there that having a reviewer like him point out the must reads and fill you in on the titles you won't be able to get to does a lot to put our own current reading and writing into perspective.